This invention relates to finely divided particulate inorganic antimony compounds, and more particularly, to antimony oxides and sulfides which are surface-modified with an organic zirconate compound.
A number of antimony compounds have been used as flame-retardants in combination with other flame-retardant for various organic resins and elastomers. One commonly used compound is antimony trioxide. One of the difficulties associated with the use of antimony compounds such as antimony oxides and antimony sulfides to improve the flame-retardant properties of flammable organic resins and elastomers is the degradation of some of the other desirable properties of the treated elastomers and resins. Although the incorporation of small amounts of antimony oxides and antimony sulfides in conjunction with organic flame-retardant compounds in flammable resins and elastomers generally improves the flame-retardant properties of the resulting products, the incorporation of such antimony compounds often has an adverse effect on other properties of the resins and elastomers such as flexural strength, impact strength, tensile strength, flexural modulus and hardness.
The above-described adverse effects are not limited to the antimony oxides and sulfides. The literature describes procedures for filling thermoplastic and other polymers with many inorganic oxides, primarily as fillers. Examples of inorganic oxides which have been used as fillers for resins and elastomers include aluminum oxide, zinc oxide, iron oxide, magnesium oxide, titanium dioxide, silicates such as kaolin clay, mica, calcium silicate and aluminum silicate, calcium carbonate such as limestone, etc. In the initial development of this art, the particulate inorganic oxide materials were introduced and blended into resins and elastomers. The resulting mixtures were molded by conventional methods such as casting, injection molding, extrusion or rotational molding to form inorganic oxide reinforced plastic articles. However, it generally was found that the properties of such filled articles were not as good as expected or desired.
Various suggestions have been made in the literature for improving the results obtained when such inorganic oxide materials are incorporated into resins and elastomers. A number of suggestions for overcoming these problems have involved the use of silicon-containing compounds, and particularly silane coupling agents.
U.S. Pat. No. 3,641,087 describes the use of brominated silane derivatives in combination with metal oxides such as antimony oxides and organic antimonates as flame-retardant additives for synthetic polymer compositions. The separate addition of metal oxides such as antimony oxide and other additives such as silanes and diallyl chlorendates to diallylic phthalate resins is described in U.S. Pat. No. 3,483,158. Such compositions are reported to be flame-retardant.
Considerable effort has been devoted to improving the flame-retardant properties of resins and elastomers in recent years, and the above discussed prior art merely is exemplary of these efforts.